Mail app built-in Mac and outlook of Mac cannot send/receive email , seems like disconnected with server , it's happened same time , about 5 PM yesterday . 

2 MAC belong to different place , different network , but internet access is normal at these two place . 

Nothing changed with exchange server and domain account . 

Rebuilt account in MAC , but still same result at all . 

For same email account , Windows / Android / iPhone / iPad / Web mail , all of them working fine . 

software version : Office Mac 2011 , Exchange 2007 , windows server 2008

Urgent Help , please . 

Thank you guys .